The present invention relates generally to an attachment assembly for connecting large excavation teeth to the loading or dipper bucket of large earth excavation equipment. Tooth attachment assemblies for large excavation equipment, typically include a number of large shanks which are spaced along and secured to the forward lip of the shovel dipper or loader bucket such that they project forwardly therefrom. A digging tooth or tooth point fits over the projecting end of each of the shanks and is secured thereto by an attachment pin.
For years, the lips of these large loader and dipper buckets comprised massive metal castings, often a foot thick, which were welded onto the bucket. Because these lips were cast, the massive size was necessary to provide the bucket lip with sufficient strength and durability to withstand the stress of large scale earth excavation. The forward edges of these bucket lips on which the shanks were mounted were not always straight, but often convexly curved or spade-shaped, as many people felt that these configurations provided superior digging characteristics. The teeth, however, must be in parallel axial alignment with the central axes of the bucket and bucket lip. To align the tooth-carrying shanks on these lips, the forward edges of the lips were formed with a plurality of projecting alignment horns which would engage the interior of the shanks and provide the desired parallel axial alignment of the shanks and the excavation teeth secured thereto. To enable earth to pass more readily over the thick blunt portions of the lips between the shanks and teeth, the forward edge of the lips were beveled. Lip protectors somewhat similar in configuration to the tooth carrying shanks, albeit smaller, were secured to the lips between the shanks to prevent damage to the forward tapered edge of the lip during earth excavation. On those bucket lips having curved or spade-shaped forward edges, these lip protectors were differently configured depending upon whether they were to be mounted on the right side, left side or in the center of the lip to obtain proper alignment of the lip protectors. Accordingly, it was necessary to provide three different configurations of lip protectors.
Because of the size and weight of these large cast bucket lips, the carrying capacity of the buckets was reduced. To decrease the weight of the lip and thereby increase the carrying capacity of the bucket, considerably thinner bucket lips were developed which were formed from thin plates of high strength alloy steel. Because these thinner plates could not be provided with integral alignment horns, it became necessary to employ three different configurations of shanks as well as lip protectors for use on the right, left and center portions of these preferred lighter weight lips employed convex or spade-shaped forward edges. In addition, without the benefit of the alignment horns which also prevented lateral movement of the shanks, the shanks had to be welded onto the lip which made shank replacement a difficult, timely and expensive process. As a result, the industry sought an attachment assembly which employed these thinner and lighter steel plate bucket lips to retain the increased carrying capacity resulting therefrom, but which could carry the tooth point mounting shanks without the need for welding to reduce the costs of shank replacement. The attachment assembly of the present invention not only satisfies this need but also obviates the need for differently configured shanks and lip protectors on bucket lips having convex or spade-shaped forward edges. The attachment assembly of the present invention, while primarily intended for use on large earth excavation equipment, is also adaptable for use on smaller excavation equipment as well.